1. Field of the Invention
This invention relates to an improved apparatus for the safe removal of hazardous particulate and/or fibrous materials, e.g., asbestos, from pipes, ceilings, and the like.
2. Discussion of the Prior Art
Asbestos has been widely used in many sectors of industry during the past fifty years, lasting up until very recent times. Pipe insulation is probably the single most common form of asbestos used in America. If the workers are not adequately protected during the removal, renovation, or demolition work involving the old insulation containing asbestos, overexposure could result.
In recent years, asbestos abatement projects have become increasingly technically sophisticated as the body of knowledge has grown regarding effective control methods. OSHA's construction standard for asbestos requires that whenever asbestos is disturbed, the work area must be sealed off from the rest of the air space. This process of isolating an area is called "containment," and involves erecting an enclosure of polyethylene sheeting to isolate the asbestos abatement area from the rest of the work area. The asbestos removal method commonly used in an abatement project includes the use of a complete walk-in-type enclosure with a negative-pressure system. This method prevents the release of asbestos fiber in order to protect bystanders from exposure to asbestos. Craftsmen working inside the enclosure are protected from exposure to asbestos fibers by wearing appropriate personal protective equipment. Use of this technique is described in OSHA's construction standard for asbestos, 29 CFR 1926.58, Appendix F.
Removal or repair of pipe insulation by itself typically presents a more localized fiber release problem than does removal of the sprayed or troweled-on asbestos insulation on larger surfaces. Some abatement methods for asbestos-containing insulation on pipes are somewhat different from methods used for removing sprayed or troweled-on surfaces. For example, when damage to pipe covering is not extensive, repair rather than removal is the recommended approach. Non-asbestos plastering can restore open joints and wrapped or plastered areas that are damaged. Glove bags may be used for removing small sections of pipe insulation, whereas the large portions of pipe insulation must be removed by erecting containment barriers and using a full range of worker protection.
Building a total enclosure presents special difficulty in pipe racks when considering the manner in which the pipes are configured. For example, it would require sealing the enclosure walls where the pipes penetrate the enclosure. When several pipes run in one or more directions, it would be extremely difficult to seal all pipe penetrations due to the limited space available between pipes. A negative-pressure walk-in enclosure for pipe racks would involve erection of a very complex and extensive barrier system. Proper planning and installation of an effective containment system can be very time-consuming and very costly.
In addition to the difficulties involved in the construction of a well-sealed negative-pressure enclosure, a further problem is the discomfort and hazards to the workers. A major problem is the possibility of heat stress resulting from the solar gains and process radiant heat. Also, pipes or process vessels containing toxic chemicals may present exposure risk to employees due to unplanned release of chemicals inside the enclosure from pressure relief valves, leaking valves, flanges and pumps.
Furthermore, the use of amended (i.e., surfactant-containing) water for wetting down asbestos creates slick walking surfaces on polyethylene and often presents a slipping hazard for employees.
The main purpose of a glove bag is to eliminate the need for constructing extensive enclosures. The goal of using the glove bag is exactly the same as the goal of erecting full-containment facilities, i.e., protecting personnel outside the containment area from asbestos exposure. While glove bags are easy to use, one problem is that the bags may rupture, resulting in the release of collected asbestos, which could create a potential exposure problem for the bystanders. Since their introduction, glove bags have inspired various types of custom uses. Recently, glove bags have been used as negative-pressure containment systems by connecting a vacuum source, fitted with a high efficiency particulate air (HEPA) filter, to a glove bag such that the negative-pressure is created inside the glove bag. This approach has not eliminated the risk of releasing asbestos in the environment, if the glove bag ruptures.
U.S. Pat. No. 4,817,644 discloses a type of glove bag adapted for multiple workers & having a centralized chute to receive asbestos particles, portions of the chute being individually sealable and separable from the remaining length of the chute.
U.S. Pat. No. 4,783,129 discloses a glove bag having shoulders removably sealed to the asbestos-covered pipe, and also having an internal zipper arrangement which is closeable to form a removeable waste catch basin.
U.S. Pat. No. 4,883,329 discloses a glove bag having an internal zipper arrangement which is closeable to form a removeable waste catch basin.
It is an advantage of the present invention that it combines the ease of the glove bag and the effectiveness of the negative-pressure enclosure system. In many situations, this approach could replace the use of a walk-in type negative-pressure enclosure.
It is a further advantage of this invention that once the hazardous material is stripped from its substrate, it does not accumulate inside the glove bag, thus eliminating the possibility of releasing significant amounts of the hazardous material in the event of glove bag damage.
It is still further advantage of this invention that it allows repeated use of the same glove bag.